July in Naperville averages a daily high of 29°C with nights around 17.6°C. Expect roughly 9.3 wet days totalling 115.6mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Naperville is August–September.
Based on AURORA WATER, IL US (13.4km), 1995–2024. 30 years of July data.